Scientists from the Food and Drug Administration have found nine “all natural” dietary supplements that contain a “non-natural” amphetamine-like compound. But then why hasn’t the FDA itself issued any kind of warning to the public about using those products?

Beats us. But tests of 21 supplements that were only supposed to contain natural ingredients found that nine didn’t have the ingredient listed on the label, Acacia rigidula, a bushy plant that grows in Texas and Mexico. Instead, those nine had something called beta-methylphenethylamine, according to the FDA scientists’ findings published in the Journal of Pharmaceutical and Biomedical Analysis.

The FDA hasn’t commented on the study or released the names of the nine found to have the non-natural ingredient, although the study was complete back in July.

“This is a brand new drug being placed into a number of supplements under the guise of a natural ingredient,” an assistant professor at Harvard Medical School told USA Today after reading the FDA study.

“The laws are incredibly weak,” the professor says. “but the FDA is not moving as fast as it could to remove hazardous products.”

The worry here is that products that list acacia rigidula — touting effects like weight loss, mood stabilizing and higher energy — could in fact be spiked with this amphetamine-like substance.

Steve Mister, CEO of the Council for Responsible Nutrition, a supplement industry group, agrees that if there is a health risk, the FDA needs to cough up a list of names and move quickly to ensure consumers are warned. Companies should be able to synthetically reproduce compounds if they’re really found naturally in plants, “but companies that are creating analogues of amphetamines and claiming they come from plants are doing something illegal and potentially dangerous for consumers.”